The invention relates to a method and apparatus for the installation of a cured in place liner within the interior of a conduit or pipeline, such as a sewer pipe, and, more particularly, to a method and apparatus for installation of a cured in place liner within the interior of a lateral conduit or pipeline which connects to a main conduit while maintaining flow through the main conduit or passageway during installation.
In a sewage system, a main sewer pipe will run underground directly along the line of a main street or thoroughfare, and the users of the system will be connected to the main sewer pipe by means of lateral pipes which extend transversely off the main sewer pipe to user points on opposite sides of the road, street or thoroughfare.
It is generally well known that conduits or pipelines, particularly underground pipes, such as sanitary sewer pipes, storm sewer pipes, water lines and gas lines, that are employed for conducting fluids frequently require repair due to fluid leakage. The leakage may be inward, from the environment into the interior or conducting part of the pipe, or outward, from the conducting part of the pipe into the surrounding environment. Leakage of this type may be due to improper initial installation of the pipe, deterioration of the pipe itself due to normal aging or to the effects of conveying corrosive or abrasive materials, cracking of the pipe or of pipe joints due to environmental conditions such as earthquakes, the movement of large vehicles or similar natural or man made vibrations, or any other such causes. Regardless of the cause, such leakage is undesirable and may result in waste of the fluid being conveyed by the pipe, in damage to the surrounding environment and in the possible creation of dangerous public health hazards.
Because of ever increasing labor and machinery costs, it is becoming increasingly more difficult and less economical to dig up and replace underground pipes, or portions or sections of such underground pipes, that may be leaking. As a result, various methods have been devised for the in situ repair or rehabilitation of the existing pipes, thereby avoiding the expenses and hazards associated with digging up and replacing the pipes or pipe sections. One of the more successful pipe repair or rehabilitation processes that is currently used is called the Insituform.RTM. Process and is described in U.S. Pat. Nos. 4,009,063; 4,064,211; and 4,135,958, the contents of all of which are incorporated by reference herein.
Briefly, in the Insituform Process, an elongated flexible tubular liner of a felt fabric, foam or similar resin impregnable material that has been impregnated with a thermosetting synthetic catalyzed resin is installed within the existing pipe. The impregnated liner may be pulled into the conduit by a rope or cable, and a fluid impermeable inflation bladder or tube is then everted within the liner. Generally, however, the liner is installed utilizing an inverting (or everting) process, as described in the latter two patents.
The flexible tubular liners generally have a smooth layer of relatively flexible, substantially impermeable material coating the outside of the liner in its initial state. This impermeable layer ends up on the inside of the liner after the liner is inverted. As the flexible liner is installed in place within the existing pipeline, the liner is pressurized from within, preferably utilizing a fluid such as water. The fluid forces the liner radially outwardly to engage and conform to the interior surface of the pipe. The resin is then cured to form a relatively hard, tight fitting, rigid pipe lining that effectively seals any cracks and that repairs any pipe or pipe joint deterioration in order to prevent further leakage either into or out of the pipe. The cured resin liner also serves to strengthen the existing pipe walls so as to provide added structural support.
More recently, there has been a demand for and a need to reline the lateral pipes as well as the mainlines. It is preferable to line the lateral pipeline using a lining tube of the same basic construction as the lining tube which is used for the main sewer pipe. A number of proposals for methods and apparatus have already been made in order to meet this requirement.
Because of the nature of the layout of main sewer pipe and laterals, it is preferable to be able to line the lateral from the mainline. This is referred to as lining from the inside out. A convenient method is to evert the lining tube into the lateral by a "launcher" type apparatus which is positioned inside the main sewer. The principal reason for proceeding in this way is that access to the lateral from the consumer point is inconvenient to the user. Frequently, users will object strongly to working for effecting lateral lining, from a position inside a dwelling or building. It is obviously much better if the contractor can perform the lining operation from inside the main sewer as the consumer is therefore in no way disturbed other than to have the service cut off for a short period while the lateral lining takes place.
Despite the existence of apparatus which are capable of installation of a lateral lining, these prior apparatus do not provide for the continued flow through of the main conduit or passageway. Often a bladder is used to forcingly mate the end of the newly installed lateral lining with the connection point of the lateral to the main conduit or passageway. The bladder expands when pressurized and fills the main conduit or passageway. Accordingly, when installation of a lateral lining is performed, the main passageway is blocked so that sewage and drainage from upstream cannot continue to progress through the main conduit or passageway.
Accordingly, it is desirable to provide an improved method and apparatus for the installation of cured in place lining of a lateral connection to a main conduit or passageway which overcomes these limitations.